Electrochemical Degradation of Fuel Cells: Effect of Electrolyte Composition

Abstract

Under some conditions, a solid oxide fuel cell (SOFC) stack can fail provided one (or more) cell(s) exhibit higher resistance than the rest of the cells. Such a cell can operate under a negative voltage prior to the onset of degradation. This phenomenon is not limited to SOFC. Recently, a model for SOFC stack degradation when a cell begins to operate under a negative voltage due to 'cell imbalance' was presented (1). Subsequently, experimental evidence for degradation was presented by investigating cell (stack) failure mechanism (2). When operated under a negative voltage of a sufficient magnitude, anode/electrolyte interface delaminated. The model shows that electronic conduction through the electrolyte plays a significant role. In the present work anodesupported cells were made of two different electrolyte compositions: 8YSZ and 92% 8YSZ + 8% CeO 2 (8CYSZ). It was observed that when operated under a negative voltage, the cell with 8YSZ exhibited considerable degradation attributed to electrolyte/anode interface delamination. By contrast, the cell with 8CYSZ exhibited no degradation under similar testing conditions. Results are explained on the basis of electronic conduction and the previously described degradation model.

Advanced air electrodes for solid oxide electrolyzer cells

“…In light of the modelling work done byVirkar (Anil V. Virkar, 2010), Lim and his co-workers (H.-T Lim et al, 2009;Park et al, 2014). increased the electronic conductivity of the electrolyte and studied its effectiveness in mitigating the delamination problem.…”

“…increased the electronic conductivity of the electrolyte and studied its effectiveness in mitigating the delamination problem. At the beginning, Lim and Virkar (H.-T Lim & Virkar, 2009). doped 8% CeO2 into the YSZ electrolyte of a Ni-YSZ|YSZ|LSM-YSZ.…”